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प्रश्न
When lead nitrate is heated strongly in a boiling tube, two gases are liberated and a solid residue is left behind in the test tube.
- Name the type of chemical reaction and define it.
- Write the name and formula of the coloured gas liberated.
- Write the balanced chemical equation for the reaction.
- Name the residue left in the test tube and state the method of testing its nature (acidic/basic).
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उत्तर
- The type of chemical reaction observed when lead nitrate is heated strongly in a boiling tube is a decomposition reaction. A decomposition reaction is a chemical reaction in which a single compound breaks down into two or more simpler products. This process often requires energy, such as heat, to break the chemical bonds in the compound undergoing decomposition.
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The colored gas liberated during the heating of lead nitrate is nitrogen dioxide (NO2), which is characterized by its brown fumes.
- The balanced chemical equation for the reaction is:
\[\ce{\underset{(Lead nitrate)}{2Pb(NO3)2(s)}->[Heat]\underset{(Lead oxide)}{2PbO(s)}+\underset{(Nitrogen dioxide)}{4NO2(g)}+\underset{(Oxygen)}{O2}}\] -
The residue left in the test tube is lead oxide (PbO). The nature of lead oxide can be tested using a litmus test. Since lead oxide is a basic oxide, it will turn red litmus paper blue, indicating its basic nature.
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संबंधित प्रश्न
Why is the amount of gas collected in one of the test tubes in the following Activity double of the amount collected in the other? Name this gas.
- Take a plastic mug. Drill two holes at its base and fit rubber stoppers in these holes. Insert carbon electrodes in these rubber stoppers as shown in the following Fig.
- Connect these electrodes to a 6 volt battery.
- Fill the mug with water such that the electrodes are immersed. Add a few drops of dilute sulphuric acid to the water.
- Take two test tubes filled with water and invert them over the two carbon electrodes.
- Switch on the current and leave the apparatus undisturbed for some time.
- You will observe the formation of bubbles at both the electrodes. These bubbles displace water in the test tubes.
- Is the volume of the gas collected the same in both the test tubes?
• Once the test tubes are filled with the respective gases, remove them carefully. - Test these gases one by one by bringing a burning candle close to the mouth of the test tubes.
Caution: This step must be performed carefully by the teacher.
- What happens in each case?
- Which gas is present in each test tube?
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- What is substance P? Write its common name as well as chemical formula.
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